Underreamer.



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APPLICATION FILED APB. 15, 1911.

L. FITZGERALD.

UNDERREAMER,

Y Patented Feb. 20, 1912.

LARRY FITZGERALD, 0F WHITTIER, CALIFORNIA.

UNDERREAMER.

Specification of Letters Patent.

Application filed April 15, 1911.

Serial No. 621,279.

To all whom it may concern:

Be it known that I, LARRY FITZGERALD, a citizen of the United States, residing at Whittier, in the county of Los Angeles, State of California, have invented new and useful Improvements in Underreamers, of which the following is a specification.

This invention relates to an under-reamer adapted particularly for use in oil wells and the like and for drilling a hole beneath the lower end of the casing of the same or larger diameter than the outside diameter of the casing; the prime object of the invention being to provide an under-reamer of simple and strong construction which may be manipulated both below the casing and within the casing without the necessity of going through special motions for tripping the cutters of the under-reamer, and so that the under-reamer may be moved up into the casing and then lowered again to its working position without the necessity of tripping as in a number of other devices.

Considered broadly, the structure embodying my invention consists of a mandrel in combination with two pivotally carried cutters, and spring means for forcing the cutters apart and stops to limit the outward movement of the critters; combined with shoulders and bearing faces for the support of the cutters when im their dierent positions.

The specific structure of my under-reamer will be best understood from the following specification and the accompanying drawings, in which- Figure 1 is a view showing my underreamer in elevation, and in its drilling position in a well. Fig. 2 is a longitudinal section of the lower portion of the reamer, showing the cutters in their closed position, and illustrating the clamp used for holding the cutters in that position when the underreamer is outside the casing. Fig. 3 is a partial side elevation of the lower portion of the mandrel. Fig. 4c is a partial side elevation of the upper portion of one of the cutters. Fig. 5 is a cross section taken on line 5 5 of Fig. 1.

In the drawings 5 designates the body of a mandrel which may be made of any size, proportions and design, having a screw threaded pin 6 on its upper end for connection with a stem (as is usual with drilling tools). Mandrel 'carries a centrally posil tioned downwardly extending tongue 7 which is of the configuration shown in Figs. 2 and 3. Below the body of the mandrel, tongue 7 is wedged shape, viewed as in Figs. 1 and 2, wit-h its opposite surfaces either straight or slightly curved as illustrated. These opposite surfaces 8 are extended upwardly into the body of the mandrel as at 9, forming the bottoms of recesses 10 which are cut in opposite sides of the mandrel immediately above the tongue 7. In the lateral walls 11 of these recesses 10 are cut grooves 12 for the reception of supporting pins 13 on the upper ends of cutters 14.

Cutters 14 are formed as is best illustrated in Figs. 2 and 5, being of such longitudinal section as to rest against surfaces 8 and 9 when the cutters are drawn in toward each other. The lower ends of the cutters are formed in any ordinary or preferred manner for eflicient drilling. Each of the cutters is supported pivotallyat its upper end by a pin 13 in grooves 12. At the upper end of each cutter is a` shank portion 15 which fits into recess 10; and immediately below shank 15 the cutter is enlarged,`presenting a shoulder 17 which bears against lower end surface 18 of the mandrel. The cutters are also extended around tongue 7 so as to form a sort of groove in the inner surfaces of the cutters, the bottom 2O of the groove bearing against surfaces 8 of tongue 7 when the cutters are closed.

Springs are utilized to force the cutters apart, and these springs are preferably arranged as shown in Fig. 2. Through the lower end of tongue 7 a bore 25 is cut in which a heavy spring 26 is housed within two cylindrical protective casings 27. Spring 26 is a compression spring and tends to press outwardly against shoulders 28, thus tending to force the cutters apart. A jointed bolt 29 passes through the spring from one cutter to the other, and this bolt may or may not be used as a stop for the movement of the cutters apart from each other. I have shown the bolt provided with a sliding loop joint, this joint providing for the movement necessary to separate and contract the cutters. The bolt is provided with heads 30 which bear against shoulders 31 and thus act as stops to the outward movement of the cutters. Plugs 32 cover the outer ends of the bolts. Above the spring arrangement just described, and located in the lower end of the mandrel body directly above tongue 7, is a second spring 35 which Patented Feb. 20, 1912.

presses outwardly against t-he inner faces of shanks 15 of cutters 14. A bolt 36 passes through spring and is preferably provided with heads 37 on its ends which act in 5 conjunction with shoulders 38 as stops to the the cutters is provided in a pin 40 which extends through the upper part of tongue 7, projecting on each side of the tongue. Extensions 11 having slots l2 therein are made on cutters 14, the slots encompassing pin 40 and allowing the cutters to move outwardly as far as illustrated in Fig. 1. The other stops previously described also allow a movement to this position and nc farther; and, although the outward movement of the cutters is sharply limited, the cutters hang loosely at all points from the mandrelthere are no solid connections which are liable to be broken by excessive strain.

lVhen the under-reamer is out of the well, the cutters may be held in their closed positions by means of such a clamp as is illustrated at 50 in Fig. 2. rlhis clamp is composed of a band 51 (preferably provided with a joint so as to be placed around the under-reamer before being withdrawing from the casing) and a screw 52 adapted to act against one of the cutters and to thereby force the cutters together. The lower ends of the cutters are placed in the casing and the clamp removed. The underreamer may then be lowered through the casing to the bottom of the well, the cutters being held closed by the casing until the under-reamer emerges from the lower end of the casing. rllhe springs then cause the cutters to immediately expand to their working position. The cutters will be kept expanded until it is desired to move the reamer from the well. Then the reamer is pulled upwardly the contact of the outer faces of the cutters with the shoe on the lower end of the cas-- ing will cause the cutters to be forced together, and the cutters will be so held by the casing until they emerge from the upper end. On account of the long gradual slope on the outer faces of the cutters, it will be seen that they are quite easily forced in wardly by an upward pull on the underreamer; the springs expanding the cutters may be extremely strong, and still the cutters may be easily forced inwardly when pulled upward into the casing. If it is desired to lower the under-reamer again this can be done without the necessity of raising it to the top of the well, as the reamer is always in condition to expand when let below the casing. Thus, with my reamer, drilling can be done immediately beneath the lower end ofthe casing; so close that the cutters enter the casing on cesses in the mandrel directly above opposite sides of the tongue, cutters loosely pivoted to the mandrel with their upper portions in said recesses, the lower portions of -the cutters being enlarged to present upwardly facing shoulders which bear against the downwardly facing shoulders of the mandrel, the lower inner portions of the cutters bearing against the tongue, spring means for expanding the cutters, a pin projecting from the tongue, and slotted eXtensions on the cutters and engaging the pin.

Q. An under-reamer, comprising a mandrel, a tongue projecting centrally from the lower end of the mandrel and of smaller size than the mandrel so as to form downwardly facing shoulders, there being recesses in the mandrel directly above opposite sides of the tongue, cutters loosely pivoted to the mandrel with their upper p0rtions in said recesses, the lower portions of the cutters being enlarged to present upwardly facing shoulders which bear against the downwardly facing shoulders of the mandrel, the lower portions of the cutters bearing against the tongue, a compression spring passing through the tongue and pressing outwardly against the cutters, a second compression spring arranged within the mandrel between the said recesses and pressing outwardly onthe cutters, and stop means to limit the outward movement of the cutters and located on the cutters between the two springs.

3. An under-reamer, comprising a mandrel, a tongue projecting centrally from the lower end of the mandrel and of smaller size than the mandrel so as to form downwardly facing shoulders, there being recesses in the mandrel directly above opposite sides of t-he tongue, cutters loosely pivoted to the mandrel with their upper pori' tions in said recesses, the lower portions of the cutters being enlarged to present up-V wardly facing shoulders which bear against the downwardly facing shoulders of the mandrel, the lower inner portions of the cutters bearing against the tongues, a compression spring passing through the tongue and pressing outwardly against the cutters, a second compression spring arranged within the mandrel between the said recesses and pressing outwardly on the cutters, and stop means to limit the outward movement of the cutters and located on the cutters between the two springs, said stop means comprising a pin projecting from the side of thetongue and slotted extensions from t-he cutters and engaging the pin.

4. An under-reamer, comprising a mandrel, a pair of cutters loosely pivoted at their upper ends to opposite sides of the mandrel, a compression spring between the cutters and pressing outwardly against them, a second compression spring arranged between the cutters below the first mentioned compression spring and pressing outwardly on the lower part of the cutters, and stop means to limit the out-ward movement of the cutters and located on the cutters between the two springs.

5. An under-reamer, comprising a mandrel, a tongue projecting centrally from the lower end of the mandrel and of smaller size than the mandrel, cutters loosely pivoted to the mandrel at their upper ends and on opposite sides of the tongue, a compression spring passing through the tongue and pressing outwardly7 against the cutters, another compression spring arranged between the cutters and pressing outwardly on them, the second mentioned compression spring being below the irst mentioned compression spring, and stop means to limit the outward movement of the cutters away from the mandrel and located between the two springs.

In witness that I claim the foregoing I have hereunto subscribed my name this 5th day of April 1911.

LARRY FITZGERALD.

Witnesses:

ELWooD BARKELEW, J AMES T. BARKELEW.

Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of Patents, Washington, D. C. 

